<!DOCTYPE html>
<html>
	<head>
		<meta charset="utf-8">
		<title></title>
	</head>
	<body>
		<script type="text/javascript">
			var a="123"
			var b="456"
			document.write(a+b+"br")
			var c=parseInt(a)
			var d=parseInt(b)
			document.write(c+d+"br")
			
			document.write(isNaN("abc")+"br")
			document.write(isNaN("123"))
		</script>
		
	</body>
</html>
